open System
open AtCoder

[<EntryPoint>]
let main _ =
    let tokens =
        Console.In.ReadToEnd().Split([| ' '; '\n'; '\r'; '\t' |], StringSplitOptions.RemoveEmptyEntries)
    let n = int tokens.[0]
    let m = int tokens.[1]
    let d = Dsu(n)
    for i in 0 .. m - 1 do
        d.Merge(int tokens.[2 + 2 * i], int tokens.[3 + 2 * i]) |> ignore
    let mutable c = 0
    for i in 0 .. n - 1 do
        if d.Leader(i) = i then c <- c + 1
    printfn "%d" c
    0